Vista - Can't establish Remote Assistance session

I'm trying to help a co-worker at home. I have a Vista 64 machine. She has
an XP sp3 machine. Both of us have Live Messenger running. Mine is Version
2009, but I think hers might be a little older. We can chat fine.

When she goes to Actions Request Remote Assistance, my PC opens a chat box
with her and I am presented with the option to Accept the request. When I
select Accept, nothing further happens. On her end, she sees a message that
I accepted the invitation and nothing further happens there either.

I would appreciate advice on settings to check and so forth. This would be
a great feature to have.

Thanks,
Dave